ImageGear v26.5 - Updated
Developer Guide / File Formats and Compressions / File Formats / File Formats Reference / DNG
In This Topic
    DNG
    In This Topic
    Full Name Digital Negative file format
    Format ID ImGearFormats.DNG
    File Extension(s) *.dng
    Data Type Bitmap (2D raster)
    Data Encoding Binary
    Multi-Page Support No
    Alpha Channel Support No
    Metadata Update Support No

    ImageGear Supported Versions

    • Version 1.0.0.0
    • Version 1.1.0.0 a fixed incompatibility in JPEG Lossless compression, added new tags

    ImageGear Supported Features

    • IGFilterFormatFlags.DETECTSUPPORT - autodetection
    • IGFilterFormatFlags.PAGEREADSUPPORT - single page file reading

    ImageGear Read Support

    • ImGearCompressions.NONE
      • Without color reconstruction: Grayscale - 16 bpp;
      • With color reconstruction: RGB - 24, 48 bpp*
    • ImGearCompressions.JPEG
      • Without color reconstruction: Grayscale - 16 bpp;
      • With color reconstruction: RGB - 24, 48 bpp*

    * 8bpc DNG loading has been enabled via promoting the image to 16bpc before loading.

    ImageGear Write Support

    None.

    ImageGear Filter Control Parameters

    Filter Control Parameter Type Default Value Available Values Description
    ApplyColorSpaceConversion bool true false, true Set to true to convert raw image to linear sRGB colorspace during loading. Has effect only if ApplyLowLevelProcessing is true.
    ApplyLowLevelProcessing bool true false, true If true, ImageGear applies initial processing stages on the Raw image. If false, ImageGear loads Raw image without any post-processing. See also ApplyColorspaceConversion and ApplyToneCorrection parameters.
    ApplyToneCorrection bool true false, true Set to true to automatically adjust image tone and apply sRGB gamma correction during loading. Has effect only if both ApplyLowLevelProcessing and ApplyColorspaceConversion are true.
    UseCameraWhiteBalance bool true false, true If true, ImageGear uses white balance settings from the file. Otherwise, white balance is calculated using ImageGear's algorithm.

    Comments

    This file format was developed by Adobe as a non-proprietary format for unified storage of "raw" images from digital cameras. DNG image stores unprocessed pixel data obtained from camera's sensor, and keeps information about color, contrast and brightness adjustments, sharpening, as well as many other parameters, in its tags. This provides greater possibilities for image correction and enhancement, compared to commonly used formats such as JPEG, EXIF or TIFF.

    The fact that the format is non-proprietary allows software vendors to provide support for DNG in their applications, with complete control over the image reconstruction process.

    By default, ImageGear automatically reconstructs colors in raw images during loading. You can disable one or more stages in the automatic color reconstruction, and reconstruct the images programmatically by using ImageGear Processing API. Use filter control parameters to disable specific stages of color reconstruction.

    DNG extends TIFF/EP format. It adds a set of new tags for parameters that control reconstruction of full color image from the raw data.

    References Used

    ADOBE SYSTEMS INCORPORATED. Digital Negative (DNG) specification.